Lightweight modeling approach for coupled heat and mass transfer during adsorption processes

Modeling the dynamics of adsorption processes is a demanding task, as the heat and mass transfer mechanisms are tightly entangled. To develop advanced adsorbent materials and devices, it is crucial to understand the relative significance of various local transport processes occurring both within the material itself and across the entire sorption component or device. In this work, authors propose a lightweight approach to model the heat and mass transfer in the adsorbent materials based on a localized lumped-parameter material model (LLMM). This model is capable of capturing the transient nature of the process. The LLMM model is based on the definition of an adimensional time characteristic of the process, which is used to determine the locality of the heat and mass transfer. The model was developed and validated for two test cases: isobaric temperature swings of a monolayer of silica gel and isochoric temperature swings of a monolith of activated carbon. The determined accuracy lies within the error of state-of-the-art experimental techniques, with a much-reduced computational effort with respect to local heat and mass transfer models. The advantage with respect to other lumped-parameter approaches, such as the linear driving force (LDF), is that the model can be applied at varying pressures and temperatures. Indeed, most of the properties utilized can be directly measured, resulting in a model that requires minimal to no calibration. Additionally, LLMM is about an order of magnitude faster than spatially discretized methods.